[dev] Performance issues with Horde Routes

[Fabio Bacigalupo]

Hello devs!

I am experiencing performance issues with Horde Routes (version 0.4).
We are using HR as part of the Seagull framework where the Horde
Routes package is integrated very nicely.

We have around 200 rules for Horde Routes to process. If I test with
just one rule the function _createGens() takes 0,16ms. With 50 active
rules the function takes around 18ms to pass. With all of them active
the same function in Horde/Routes/Mapper.php takes a bit more than
1000ms on every page request to execute. It seems there is a
correlation between the number of rules and the execution time which
increases drastically on every rule added after a certain point.

It's no surprise looking at the code of _createGens() which iterates
through the list of rules three times.

Has anyone else had the same issues? Did you find a solution? Is there
an easy way to improve speed here? Is there a way to cache Horde
Routes somehow?

Thank you,
Fabio Bacigalupo.